Process for the production of liquid compositions

ABSTRACT

A process for producing a liquid composition containing at least one active component and a diluent by mixing the active with diluent and/or liquid active to produce a liquid crystal mixture and incorporating diluent into it such that the mixture remains substantially homogeneous to produce a composition in which the concentration of active components is lower than the concentration of active components in the liquid crystal mixture. Novel apparatus for use in the process is also described.

FIELD OF THE INVENTION

This invention relates to a process for the production of liquidcompositions. In particular the invention relates to a process for theproduction of a structured liquid composition. The invention alsorelates to a liquid composition produced by such a process and to anovel apparatus for use in the process.

BACKGROUND OF THE INVENTION

Structured liquid compositions are found in many products includingfoods, for example margarines and low fat spreads, cosmetics andpersonal care products and detergents products, for example liquiddetergent compositions and fabric conditioning compositions.

Generally, liquid compositions, which include solutions, gels anddispersions, are produced by simple mixing of the components of thecomposition. The active materials which may be liquid or solid aretypically added to a liquid solvent, for example water in the case ofaqueous compositions, and agitated and optionally heated to produce theliquid composition. Many liquid compositions are generally producedusing a stirred batch mixer.

Simple mixing to produce a liquid composition conventionally involvessubjecting the components to relatively low deformation rates in themixing process whereby a mechanical shear effect is imparted to thecomposition. A typical process for the production of a liquid, forexample a liquid detergent composition, may involve a shear deformationrate for example of the order of 10⁴ sec⁻¹ being applied to thecomponents of the composition.

Conventional liquid compositions generally contain a relatively lowlevel of active material due to difficulties encountered in processing.Such difficulties arise as the viscosity of the mixture of the activeand liquid solvent generally increases with a higher level of activewhich may lead to production of an inhomogeneous mass of highly viscousand shear thinning intermediate compositions. Such compositions aredifficult to disperse in mixing processes and conventional apparatus asuncontrolled phase separation may occur. Moreover, the effectivefunctioning of the mixing apparatus may be compromised or the requiredenergy input may be prohibitively high at high viscosities.

In some processes, the active components for example oil and surfactantmay be mixed initially prior to mixing with the liquid solvent and maybe solid. In order to secure adequate mixing, the active mixture istypically heated to a temperature above the melting point of the activecomponents if solid. Heat transfer in such mixtures is typically poordue to the generally high viscosity of the active mixture and thuspresents further processing difficulties.

Thus, the conventional processes in which the active components areincorporated into the liquid solvent and the concentration of theactives remains constant or increases during the process exhibit severaldrawbacks. These problems include shear thinning effects, inefficientoperation of the mixing apparatus and poor heat transfer. Consequentlycareful selection of active components and the levels to be incorporatedis required especially if the active component comprises a solid. As apractical drawback, the flexibility in formulation may be somewhatlimited due to the sensitivity of the process to variations informulation.

EP 580,263 discloses a process for preparing a concentrated liquidaqueous solution of a salt of an alkyl ether carboxylic acid salt andoptionally adding thereto an ethoxylated and optionallycarboxymethylated product derived from a polyhydric alcohol The mixturemay then be diluted with water. In the Examples, a homogeneous "paste"is produced which is then diluted with water to the desiredconcentration. On the basis of the components disclosed, it appears thatthe "paste" is a concentrated solution of surfactants some of which mayact as a hydrotrope. It is noted that the water is incorporated by asimple mixing process and controlled addition of the water to the pasteto maintain homogeneity and avoid uncontrolled phase separation does notappear to be necessary.

GB1523678 discloses a process in which oil is added to water to producean oil in water concentrated emulsion and then diluted with water to thedesired composition. The process steps are conducted over a long period(hours) and this may represent a serious disadvantage.

SUMMARY OF THE INVENTION

We have found that these problems may be alleviated by mixing at leastone active component with a liquid component of the composition toproduce a viscous mixture, for example a paste, homogenising the mixtureand gradually incorporating a diluent into the mixture whilstmaintaining the homogeneity thereof in order to produce a compositionhaving the desired concentration of active components. The diluent isadded to the homogeneous mixture of active components in a controlledmanner whereby the concentration of active component in the mixturedecreases during the addition to produce the liquid composition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a, 1b and 1c show a cross section of a stator and a plan view ofthe rotor journalled within the stator with the rotor in, respectively,an advanced, retracted and zero-offset position in relation to thestator.

DETAILED DESCRIPTION OF THE INVENTION

Accordingly a first aspect of the invention provides a process forproducing a liquid composition comprising at least one active componentand a diluent which comprises mixing an active component of the liquidcomposition with a liquid active component and/or diluent of the liquidcomposition to produce a liquid crystal initial mixture andincorporating a diluent into the initial mixture wherein the diluent isincorporated such that the mixture remains substantially homogeneousduring the said incorporation to produce a substantially homogeneousliquid composition having a concentration of active components less thanthe concentration of active components in the said initial mixture.

Preferably the initial mixture has a viscosity of at least 4000 mPas,and preferably at least 10000 mPas at a shear rate of 21s⁻¹

By `homogeneous` we mean a mixture which exists as a single phase, forexample a liquid crystal phase and an isotropic liquid, a uniformdispersion of the diluent in the active mixture, or a uniform dispersionof the active mixture in the diluent. The homogeneous mixture may beplanar lamellar or vesicular lamellar in structure. Maintaininghomogeneity of the mixture does not imply that it must remain in onephysical form during the process but that, if the physical form doeschange then each physical form should be homogeneous. It is thereforewithin the scope of the invention for the initial mixture to be presentas a single phase and then become a multiphase mixture during theaddition of the diluent, for example continued addition of the diluentmay produce a dispersion from a single phase mixture. It is essentialthat uncontrolled phase separation does not occur.

Homogeneity can be considered as being maintained if either, the processrun, when repeated, provides products from the runs which have relativerefractive indeces which are within points of each other, or in acontinuous process the variation in relative refractive index of theproduct produced at different points in the process is no more than 2.

Relative Refractive Index may be calculated by multiplying thedifference between the Refractive Index of the final product and that ofthe diluent (for example water in aqueous products) by 1000. RefractiveIndex may be determined using a conventional refractometer.

By adding the diluent to the active mixture to decrease theconcentration of active whilst maintaining homogeneity liquidcompositions having high active levels may be produced and flexibilityin formulation may be secured which in the conventional process wouldpresent processing difficulties due to the difficulty of mixing aviscous paste in a conventional batch mixer.

The process may be employed to produce an isotropic liquid compositionfor example a liquid detergent composition but is especially beneficialin producing a structured liquid composition.

We have found that problems associated with the conventional process forproducing structured liquid compositions may be further alleviated bysubjecting the homogeneous mixture to a high rate of deformation,particularly extensional deformation.

Accordingly, a second aspect of the invention provides a process for theproduction of a structured liquid composition comprising an activecomponent and a diluent which comprises:

i) mixing an active component of the composition with a liquid activecomponent and/or part of the diluent to produce a substantiallyhomogeneous liquid crystal mixture;

ii) incorporating diluent to saturate the liquid crystal mixture withrespect to the diluent whereby a substantially homogeneous continuousphase comprising the active component and diluent, and optionally adispersed phase comprising the diluent, is produced;

iii) producing a substantially homogeneous dispersion of the saturatedliquid crystal mixture in a continuous diluent phase;

iv) optionally diluting the dispersion with further diluent to providethe desired concentration of active component.

The liquid crystal mixture may be in any known form such as a hexagonal,reversed hexagonal, cubic or lamellar phase mixture.

It is an essential feature of the invention to maintain substantialhomogeneity in the mixture whilst incorporating further diluent and, ifpresent, during the phase inversion step for example between steps ii)and iii) according to the second aspect of the invention. The diluent issuitably incorporated in a plurality of doses in step i) and preferablystep ii) with rapid mixing and in such a quantity that substantialhomogeneity is maintained.

Preferably the phase inversion step, if present, is conducted under ahigh deformation regime. High deformation of the process mixture permitsstress to be transmitted to the dispersed phase such that homogeneitymay be maintained. The diluent phase is generally less viscous than theactive phase and following inversion the mixture is suitably subjectedto extensional deformation whereby stress is transmitted to thedispersed phase. Shear deformation is also generally desirable in thephase inversion step.

By "active component" we mean a component of the liquid composition,other than the diluent, which affects the rheology of the processmixture during the incorporation of the diluent. For example, in thecase of a liquid detergent composition, an anionic surfactant and/or anonionic surfactant may constitute the active component(s) and water mayconstitute the diluent. Other active components may be present asdesired. The `active component(s)` may be present in the process inliquid form but may include solids which are soluble in any of the othercomponents in the composition as such material will influence therheology of the process mixture.

The diluent constitutes that liquid or liquids in which the activecomponents are dispersed and/or dissolved in the liquid composition, forexample, water constitutes the diluent in an aqueous rinses conditioneror an aqueous liquid detergent composition. If desired a plurality ofdiluents maybe employed and the diluent added at each point in theprocess may be the same or different to that added elsewhere.

This process allows a significant broadening of the formulationflexibility in the processing of liquid compositions as a wider varietyof components may be incorporated and compositions having a higherconcentration of active materials may be produced than was hitherto thecase. Improved process flexibility is secured, for example the optimalorder of addition of the active components may be determined andtolerated in the process and the diluent may be introduced at a varietyof points in the process. Under extreme processing conditions forexample, during deformation during phase inversion a fine structure maybe produced in the composition and may be closely controlled. This hasthe benefit of facilitating the production of a composition havingconsistent physical characteristics and therefore less product variationduring a production run.

The active component may be a liquid or a solid. Further, a plurality ofactive components may be employed as desired and may be mixed to producea premix of active components. The premix may then be mixed with thediluent or a liquid active component in step i) to produce the liquidcrystal mixture. The active component may be mixed with the diluentand/or liquid active component sequentially and/or simultaneously and,if desired, may be introduced into the process as a solution ordispersion in the diluent and/or a liquid active component in step i)and/or ii).

Incorporation of diluent in step i) and/or ii) may be conducted atelevated temperature, especially if the active component is solid atambient temperature in which case the temperature is suitably above themelting point of the solid active component.

Optionally in step i), the active component and the diluent and/orliquid active component may be subjected to a deformation regime whichmay contain a shear flow and/or an extension flow element to aid themixing, homogenising and formation of the liquid crystal mixture.

The liquid crystal mixture is suitably a paste and generally comprisesat least 50%, preferably at least 65%and especially in excess of70%active component. Suitably the diluent and/or liquid active componentconstitutes the balance of the mixture. The liquid crystal mixture maybe a dispersion, emulsion or suspension. The liquid crystal mixture maybe lamellar depending on the active component(s), diluent and theirrelative amounts.

It is especially preferred that a part of the diluent be incorporatedinto the liquid crystal mixture subsequently to its formation and morepreferably that a plurality of subsequent charges of the diluent beintroduced in step-wise fashion as this facilitates the maintainence ofa substantially homogeneous liquid crystal mixture.

By this process step, the ratio of active component to diluent changesand, more specifically decreases during the formation of the liquidcrystal mixture.

Suitably, where the liquid crystal mixture is lamellar, the temperatureof the lamellar mixture is controlled to ensure that the mixture is inor passes through the Lα phase during the addition of the diluent to theinitial mixture. Suitably, the mixture with further addition of diluentpasses directly or indirectly through intermediate phase(s) into the L₁+L α phase. Depending on the type of composition, the mixture may passinto the L₁ +Lβ phase on cooling in which the molecule chains arerelatively immobile. It is generally preferable to dilute the mixture tothe final desired concentration at a temperature above the L₁ +Lα/L₁ +Lβphase transition temperature as this suitably provides a product havinga lower viscosity.

A further aspect of the invention provides a homogeneous lamellarmixture having an active component layer and a diluent layer obtainableby, and preferably obtained by, a process comprising mixing an activecomponent with a liquid active component and/or diluent of thecomposition to produce a initial mixture which is preferablysubstantially homogeneous, and incorporating diluent into the saidinitial mixture wherein the diluent is incorporated such that themixture remains substantially homogeneous during the said incorporationto produce a substantially homogeneous lamellar mixture having aconcentration of active component less than the concentration of activecomponents in the said active mixture.

The surprising storage stability of the homogeneous mixture has thepractical benefit that the dilution step in the first part of theprocess may be only partly completed or, the dilution step and, ifpresent, the phase inversion step may be decoupled. Thus production ofthe homogeneous mixture may continue if the phase inversion step isinoperable and, if desired the production may be carried out ondifferent sites.

As high viscosities are encountered in the steps i) and ii) conventionalmixing apparatus is generally not suitable for use. A conventionalextruder suitably equipped with a conveying screw preferably twin intermeshing conveying screws, has been found to provide an excellentapparatus in which to mix the active component with the diluent and/orliquid active component as the components may be forced through it thusapplying deformation and providing intimate and rapid mixing to producethe homogeneous, liquid crystal preferably lamellar, mixture.Furthermore the extruder may be used to force the components through thesubsequent steps in the process if the apparatus employed in such stepsdoes not provide a conveying function.

Desirably the extruder has a plurality of inlet ports along its lengththrough which active component and especially diluent may be introducedin one or more successive charges. The process may be batch but ispreferably continuous, the extruder being particularly suitable for usein a continuous process.

The further diluent is incorporated into the liquid crystal mixture tosaturate it and may cause the mixture to undergo a phase inversion to adispersion of a saturated liquid crystal-in-diluent system and/or adiluent-in-saturated liquid crystal-in-diluent system. Suitably thefurther diluent is mixed with the liquid crystal mixture prior to andoptionally during the phase inversion step if present.

Phase inversion-is preferably induced by subjecting the saturated liquidcrystal mixture to a high deformation rate.

The saturated liquid crystal mixture suitably comprises at least 20%,and preferably at least 25% by weight of active component. Suitably thediluent constitutes the balance.

Where the continuous diluent phase of the substantially homogeneousdispersion is less viscous than the dispersed saturated liquid crystalphase following phase inversion, as will generally be the case,extensional deformation effects the transmission of stress to thedispersed phase such that continued mixing results to maintain asubstantially homogeneous dispersion. Desirably, shear deformation isimparted to the dispersion in addition to extensional deformation.

The deformation rate and preferably extensional deformation rateemployed will be determined by the type of composition being processed,for example a rinse conditioner composition will generally be subjectedto a deformation rate of at least 3×10³ sec⁻¹. Heavy duty liquids areoptimally processed using a deformation rate of preferably 3×10³ to 10⁵sec⁻¹. Preferably the deformation rate is more than 10⁴ sec⁻¹, morepreferably 3×10⁴ sec⁻¹, for example 10⁵ sec⁻¹.

In especially preferred processes, the process stream is subjected toshear at a level of more than 3×10³, more preferably at least 10⁴ s⁻¹,extensional flow at a level of 3×10³, more preferably at least 10⁴ s⁻¹or even more preferably to both extension and shear at these levels orabove.

If a combination of extension and shear deformtion are employed we havefound that the overall deformation rate required in a particular case islower than that required if either extensional or shear deformationalone were to be employed.

The high deformation regime intensifies the structuring process andpermits highly viscous mixtures to be processed such that high levels ofactive components may be incorporated into the composition.

Control of temperature and deformation rate provides a means by whichcrystallisation of an active component for example a liquid surfactantmay be secured.

A further aspect of the invention provides a substantially homogeneous,structured dispersion having a dispersed phase containing an activecomponent and a diluent and a continuous phase containing a diluentobtainable by, and preferably obtained by, providing a substantiallyhomogeneous liquid crystal mixture having an active component layer anda diluent layer, incorporating further diluent to saturate the mixtureand to produce a substantially homogeneous dispersion of the diluent ina continuous saturated liquid crystal phase, subjecting the saturatedmixture to deformation whereby the phases are inverted and stress isimparted to the dispersed active phase to produce a structuredsubstantially homogeneous dispersion.

The dispersion suitably has an average droplet size of less than 10 μm,preferably less than 5μm and desirably 0.01 to 4 μm, for example 1 μm.We have found that by operating according to the process of the presentinvention that for a given composition and viscosity that asignificantly reduced droplet size may be obtained. The providesdispersions having excellent storage stability.

The droplet size may suitably be measured using a light scatteringinstrument for example a Malvern Mastersizer.

The deformation step has the further advantage that bacteria present inthe process mixture or processing apparatus may be destroyed due to cellrupture under a high deformation regime. Under static conditions apressure of the order of 5000 bar is generally required to kill bacteriahowever in the present process a combination of high pressure anddeformation together is more effective than static pressure indestroying bacteria and the process conditions of the present inventiontherefore provide a micro biologically "clean" composition. Thedeformation step may be carried out in any apparatus in which highextensional deformation rates may be obtained. A preferred apparatus inthis regard is described below.

The structured liquid composition obtained from the deformation step issuitably subjected to further processing according to the particularapplication. As the composition will generally contain a high level ofactive component, dilution of the composition with further diluent toadjust the concentration of the active component is generally desirable.Such further dilution is desirably controlled as regards the rate ofaddition of the diluent and rate of mixing in order to maintain thesubstantially homogeneous characteristic of the dispersion.

The present invention is especially applicable to the production of astructured cleaning liquid for fabrics or hard surfaces, and personalwashing products, suitably wherein at least one surfactant is present asan active component, and-water is present as the diluent. Fabricconditioning compositions containing an organic cationic quaternaryammonium compound as an active component and water as the diluent mayalso be produced. The liquid composition may contain a plurality ofdispersed liquid crystalline phases and other dispersed liquid and/orsolid phases as desired.

The process according to the invention is particularly suited to theproduction of liquid compositions containing as an active component, oneor more anionic, nonionic, cationic and/or zwitterionic surfactantsknown in the detergents art and wherein the diluent is water and/or asurfactant which is immiscible with the surfactant active component.

Examples of suitable surfactants which may be employed include,alkylbenzene sulphonates, alkyl sulphates, alkyl ether sulphates, olefinsulphonates, xylene sulphonates, soap and alcohol alkoxylates, any ofwhich preferably have a C₉ to C₂₂ alkyl chain. Alcohol alkoxylates andalkylbenzene sulphonates more preferably have an alkyl chain length of 9to 15 carbon atoms.

Suitable alkoxylated, preferably ethoxylated, materials may have anaverage degree of alkoxylation of 1 to 40 depending on the application.For a fabric washing composition the degree of alkoxylation ispreferably 1 to 15, preferably 1 to 10 and for a fabric rinseconditioner preferably 10 to 25.

Fabric conditioners suitably contain a cationic surfactant, preferably aquaternary ammonium compound at a level of 1 to 30%, preferably from 1to 10% for a dilute conditioner product and preferably from 10 to 30%,especially 10 to 25% for a concentrated product. Examples of suitablecationic surfactants are disclosed in EP239910, the disclosure of whichis incorporated herein by reference.

Fabric washing compositions, in addition to the usual anionic andoptionally nonionic surfactant, typically include a builder material.Suitable builders include phosphates such as tripolyphosphates andzeolites especially of the A and P type.

Other components may be included in fabric washing compositions asdesired and include polymers, such as homo or copolymers of acrylicacid, maleic acid or anhydride; electrolytes such as inorganic salts forexample citric acid, citrate and chloride salts of alkali metals, andglycerol and borax; other conventional components such as carbonate andsilicate alkali metal salts and minor ingredients. If desired, enzymesand/or bleach, for example alkali metal percarbonate may be included inthe composition.

Components in the liquid composition may be present at conventionallevels or even higher levels as the present process allows suchmaterials to be processed at levels where ordinarily, the viscositywould be prohibitively high for a conventional liquid production processto be used.

The deformation step is preferably carried out in a novel mixercomprising confronting surfaces, each having a series of cavities formedtherein in which the surfaces move relatively to each other and in whicha liquid material is passed between the surfaces and flows along a pathsuccessively through the cavities in each surface and is subjected toextensional deformation and/or shear deformation and preferably bothextensional and shear deformation.

A mixer is known in which the cavities are arranged on the relevantsurfaces such that shear is applied to the liquid as it flows betweenthe surfaces. The cavities are arranged on the respective surfaces suchthat there is a relatively small change in the effective cross-sectionalflow area as the material passes through the mixer. In such mixers,primarily distributive mixing is obtained. Generally the cross-sectionalarea for flow varies by a factor of less than 3 through the apparatus.Shear is applied by the relative movement of the surfaces in a generallyperpendicular direction to the flow of the material there between. Thisapparatus is described in EP 194 812.

It has been found that, in addition to shear, significant extensionalflow and efficient distributive and dispersive mixing may be secured byproviding an apparatus having confronting surfaces and cavities thereinin which the cavities are arranged such that the cross-sectional areafor flow of the liquid successively increases and decreases by a

factor of at least 5 through the apparatus. The invention furtherprovides a dynamic mixing apparatus for inducing extensional flow in aliquid composition which comprises closely spaced relatively moveableconfronting surfaces each having a series of cavities therein in whichthe cavities on each surface and are arranged such that, in use, thecross-sectional area for flow of the liquid successively increases anddecreases by a factor of at least 5 and preferably at least 10 throughthe apparatus.

Preferably, each confronting surface has at least one ring of cavitiesarranged therein such that the cavities in each ring are positionedequidistant or near equidistant from the common axis of rotation and lieon or may be intercepted by a plane normal to the common axis ofrotation. The ring(s) of cavities on each surface are suitably arrangedrelative to each other such that the cross-sectional area for flowavailable for material during passage through the apparatus successivelydecreases and increases by a factor of at least 5, and preferably atleast 10. Optionally, the cavities in the confronting surfaces areoffset relative to each other and so may overlap.

Suitably the confronting surfaces each comprise at least 2 andpreferably at least 3 rings of cavities. Suitably, the cross-sectionalarea for flow increases or decreases by a factor of at least 5 betweenadjacent pairs of rings of cavities on each confronting surface.

Preferably, the confronting surfaces have a common axis of rotation andare generally complementary. One or both surfaces may be moveable asdesired, the only requirement being to ensure that there is relativemovement between the surfaces. The confronting surfaces may be of anysuitable configuration but conical, planar, in which case the axis ofrotation is perpendicular to the plane, and especially cylindrical arepreferred.

If desired, 2 or more pairs of confronting surfaces may be employed fora single process stream pathway. For example, in a cylindricalarrangement, concentric pairs of confronting surfaces may be providedthus defining concentric pathways. The pathways suitably communicate inorder to provide a continuous process stream pathway.

Suitably the temperature of the surfaces is controllable, thus it ispreferable that the apparatus be equipped with thermal control means,for example cooling/heating jackets, for this purpose.

Apparatus having a cylindrical geometry may comprise a stator withinwhich is journalled a rotor; the opposing faces of the stator and rotorcarry the cavities through which the material passes during its passagethrough the device. The cavities in the stator and rotor are suitablyarranged such that they are generally aligned or slightly offset in anaxial direction whereby the material passes from a cavity in one througha constricted pathway defined by the confronting surfaces into a cavityin the other, during which passage the cross-sectional area for flowdecreases and increases by a factor of at least 5, and more preferablyat least 10.

The apparatus provides a mixer in which the modes (extension and shear),degrees, rates and times of deformation are controllable, quantifiableand, hence, optimisable with respect to the process material. Thisprovides for excellent process control, flexibility and manipulation.

The process material is suitably mixed by shear deformation during eachtransfer across the annulus formed between the rotor and stator. Acontrolled extensional deformation is introduced via the relative axialoffset positions of cavities on the rotor and stator, and is a maximiumwhen the axial offset is reduced to its limit of zero. The processmaterial is also preferably subjected to shear deformation as it isextended.

The invention also provides for the use of the novel dynamic mixingapparatus as herein described for the production of a liquid, gel orother fluid composition.

Apparatus of the invention is described further hereinafter, by way ofexample only, with reference to the accompanying drawings in which FIGS.1a, 1b and 1c show a cross section of a stator and a plan view of therotor journalled within the stator with the rotor in, respectively, anadvanced, retracted and zero-offset position in relation to the stator.

In particular, the illustrated embodiment of the apparatus consists of acylindrical rotor (1) which rotates within a cylindrical stator (2)during normal operation, the rotor (1) and stator (2) each having sixcircumferential rows of equal sized cavities spaced along their axialdimension. Each circumferential row on the rotor has eight cavities (3)and each row on the stator has eight cavities (4). Typically, thecavities are elliptical in shape and have an axial dimension which isabout twice the cavity width maximum width which is itself about twicethe cavity depth.

The rotor (1) may be positioned in either `advanced` or `retracted`positions as shown in FIGS. 1a and 1b, respectively. The words`advanced` and `retracted` describe the relative axial positions ofcircumferential rows of cavities on the rotor (1) (3) to those on thestator (2) (4) when compared to those for the zero axial off-setposition shown in FIG. 1c having regard to the direction of flow of theprocess stream. In the advanced position the extensional flow occursprimarily during passage from the rotor (1) to the stator (2), whereasin the retracted position the extensional flow occurs primarily duringpassage from the stator (2) to the rotor (1). Shear is imparted to theprocess stream by the relative movement of the rotor (1) and the stator(2).

The invention is illustrated by the following non-limiting Examples. Thefollowing Table lists various components employed in the Examples.

    ______________________________________                                                    Commercial Abreviation/                                             Chemical name Name used Manufacturer                                        ______________________________________                                        Distearyidimethyl                                                                         Varisoft   Varisoft  Witco GmbH                                     ammonium chloride TA100 TA100                                                 Sulphonic acid Petrelab LAS Petresa                                            550                                                                           Vista SA LAS Vista Chemicals                                                  5197 (Vista) Company                                                         Na alkylbenzene UFARYL DL Na LAS Unger Fabrikker                              sulphonate 80W  A.S.                                                          Alcoholethoxylate Neodol Neodol Shell                                         C.sub.12-15  9EO 25-9 25-9                                                    Alcoholethoxylate Synperonic Synperonic ICI                                   C.sub.13-15  7EO A7 A7                                                        Alcoholethoxylate Synperonic Synperonic ICI                                   C.sub.13-15  3E0 A3 A3                                                        Coconut acid Prifac Prifac Unichema                                            7904 7904 International                                                      Oleic acid Priolene Priolene Unichema                                          6907 6907 International                                                      Citric acid  Citric Pfizer                                                    (anhydrous)  acid                                                             Tri sodium  Sodium John & E Sturge                                            citrate  citrate Ltd                                                          NaOH (47%)  NaOH Ellis & Everard                                              KOH (49%)  KOH Ellis & Everard                                                Glycerol  Glycerol Unichema                                                   Borax decahydrate  Borax Borax Francais                                       Acrylic copolymer Narlex Narlex National Starch                               (33%) DC1 DC1                                                                 Derivative of a Tinopal Tinopal Ciba-Geigy                                    distyryl biphenyl CBS-X CBS-X                                                 Silicone antifoam Q2-3300 Antifoam Dow Corning Ltd                            Na diethylene Dequest Dequest Monsanto                                        triamine penta 2066 2066                                                      (methylenephospho                                                             ric)                                                                          Zeolite Vegabond Vegabond NV Soprolit SA                                       Wessalith Wessalith Degussa                                                   P P                                                                          Sodium Silicate  Sodium Crossfields                                           (40%)  silicate Chemicals                                                     Sodium Xylene Manrosol SXS Manro Products                                     Sulphonate SXS40  Lyd                                                         Sodium carbonate  Sodium Brunner Mond                                           carbonat                                                                    Calcium Chloride  Calcium BDH                                                   Chloride                                                                    Aq sol of sodium Sokolan  BASF                                                salt of PA50                                                                  polyacrylic acid                                                            ______________________________________                                    

EXAMPLE 1

A series of fabric conditioning compositions were produced by a processaccording to the invention by feeding into a

Werner Pfleiderer co-rotating twin screw extruder, a fabric conditioningcompound (VARISOFT), as the active component, at a feed rate of 25 kg/hrand water, as the diluent, through an inlet in the barrel wall at a feedrate of 6 kg/hr and a temperature of 90° C. The components were mixed toproduce a substantially homogeneous liquid crystal mixture containing80wt% active component and 20wt% diluent.

Further water was then incorporated slowly into the mixture to produce asubstantially homogeneous saturated or near saturated liquid crystalmixture having a temperature of 50 to 60° C. and containing 30wt% activeand 70wt% water.

This mixture was then fed into a dynamic mixer according to theinvention with sufficient ambient water to produce a mixture having anactive composition of between 5 and 12 wt %. In passing through themixer, a homogeneous dispersion of water in active was produced by theinversion of the liquid crystal phase and the saturated diluent.

The mixer had an internal diameter of 50 mm, a rotor length of 270 mmand was operated at a rate of rotation of 1400rev/min. The cavitiesextended along the rotor and the stator and in passing between cavities,the mixture was constricted by passage through a cross sectional flowarea of less than 0.2 times the cross sectional flow area through thecavities.

The viscosity of the resulting compositions (in mpas) was measured at110 sec⁻¹ and 25° C. The results are illustrated in Table 1.

Comparative Examples A and B

Compositions containing the same components as those produced in Example1, ie between 5 and 11% VARISOFT fabric conditioning active component inwater, were produced by conventional processes for the production ofliquid compositions.

In Example A, the water was placed in a stirred vessel and active wasadded under stirring to the desired concentration. The mixing wascarried out at elevated temperature in order to melt the active.

In Example B, compositions produced in Example A were subjected to aconventional post shear process to improve the viscosity characteristicsof the final composition.

On visual inspection, compositions A and B were clearly moreinhomogeneous as compared with example one especially at a high activelevel.

                  TABLE 1                                                         ______________________________________                                        Active (%)   Example 1 (viscosity)                                            ______________________________________                                        5            40                                                                 8 65                                                                          11 155                                                                      ______________________________________                                    

The results illustrate that the process of the present invention may beemployed as an alternative process route to conventional routes. Anadvantage of the process of Example 1 is that in heating the active inorder to mix it with the water, only a proportion of the water need beheated whereas in Examples A and B, all of the water had to be heated.

EXAMPLE 2

An isotropic fabric washing liquid was produced by the followingprocess. A paste (initial mixture) was formed in a 25 L batch mixer ofthe Z blade type. The ingredients were added in the order shown in Table2.1 with the paste containing no added water. The paste was in acontinuous liquid crystal phase and had a viscosity in excess of 20,000mPas at 40° C. & 20/s. The paste was then injected into a continuoushigh shear mixing device (a cavity transfer mixer as described inEP194812 and then passed into a shear/extension zone as described inExample 1 and herein with reference to the accompanying figures). Water(diluent) at 80° C. was then mixed with the paste at 4 separate pointsas detailed in Table 2.1 and incorporated rapidly to maintainhomogeneity to form the final product which was isotropic The first twodilution streams were added prior to the extension zone, the third wasadded midway along the extension zone and the final stream was added atthe end of the extension zone.

                  TABLE 2.1                                                       ______________________________________                                                           Stages 2-5.                                                                             Prior to                                           Stage 1 Dilution extension                                                    Paste (%) streams (%) zone                                                  ______________________________________                                        LAS acid (Vista)                                                                          12.3                                                                NaOH (49%) 3.5                                                                Neodol 25-9 4.5                                                               Sodium Silicate 2.5                                                           SXS 1.0                                                                       Total paste 23.8  Yes                                                         Water Dilution 1  17.8 Yes                                                    Water Dilution 2  17.8 Yes                                                    Water Dilution 3  17.8 mid point                                              Water Dilution 4  22.7 No                                                     Total Diluent  76.1                                                         ______________________________________                                    

During the continuous run, the flow and deformation conditions werevaried as detailed in Table 2.2. If homogeneity is not maintainedresidual amounts of undispersed paste are present in the product andappear as undesirable small flecks. These products are thus prepared bya comparative process not according to the invention.

                  TABLE 2.2                                                       ______________________________________                                                               Extension                                                Product Shear rate Rate                                                       flow rate (×10.sup.3 /s) (×10.sup.3 /s) Product                 ______________________________________                                        360 kg/hr 9            0        flecks                                           14.1 0 smooth                                                                 4.1 7.1 smooth                                                               510 kg/hr 9 0 flecks                                                           19 0 flecks                                                                   24 0 smooth                                                                   9 10.1 smooth                                                              ______________________________________                                    

Product viscosity was in all cases about 200 mPas. The results show thatshear alone is sufficient to disperse the high active paste ifhomogeneity is maintained but that application of shear in combinationwith extensional flow using for example the apparatus described in FIG.1 allows homogeneity to be maintained at a lower value of the shearcomponent of the flow. It is observed that an increased flow raterequires higher levels of minimum shear both with and without extensionto maintain homogeneity and so disperse the paste. Increasing theextension rate at given operating conditions, for example by increasingthe variation in cross-sectional flow area in the extension zone, thenthe minimum shear rate required can be reduced. Example 3

A fabric rinse conditioner composition was produced by the followingprocess. VARISOFT powder was steadily fed (25 kg/hr) into a W&P extruderwith water (6.25 kg/hr) (diluent) to form an 80% active paste (initialmixture)having a viscosity of about 400 mPas at 20/s. The mixture washeated to above 95° C. in order to melt the active and below 130° C.above which the water will tend to boil off. The screw elements andscrew speed were selected to thoroughly mix the active and water andalso to ensure that the high temperature (>100° C.) zones operate atsufficient pressure to prevent water turning to steam. The extruder fedthe paste directly into a mixer as used in Example 2 where it wasdiluted further with demineralised water (50-70° C.). Diluent was addedafter the extensional flow zone at ambient temperature. The flow ratesemployed are detailed in Table 3.1 and the deformation rates are shownin Table 3.2. During the continuous process the level of diluentintroduced into the mixer was varied to produce an active concentrationof 15 to 40% (see Table 3.2) and the level of diluent subsequentlyincorporated adjusted to give a final concentration of 5%.

The particle/droplet size of the products was measured. A smallerparticle size providing improved storage stability.

                  TABLE 3.1                                                       ______________________________________                                                Flow rates                                                                             Temperature                                                                             Active                                               (kg/hr) (° C.) concentration                                         ______________________________________                                        Varisoft  25                                                                    TA100   95-130 80%                                                            Demin water 6.25                                                              Demin water 138->32  50-70 15->40%                                            Demin water 330->435 20-40 5%                                               ______________________________________                                    

Control samples were also made using a conventional standard process ina 3 L stirred tank followed by post shear (PS) in an Ultra-turrex highshear mixer (see respectively Control 1 and 2 in table 3.2). Products ofgreater than about 10-12% active could not be made.

                  TABLE 3.2                                                       ______________________________________                                                  Active              Extension                                                                            Mean                                       Sample conc.after Shear Rate Rate particle                                    number dilution (×10.sup.3 /s) (×10.sup.3 /s) size (μm)      ______________________________________                                        Control 1 NA       0.1-0.5    0      9.2                                        Control 2 NA 30 0 3.7                                                         1 37 14.7 0 4.0                                                               2 37 14.7 14.1 2.8                                                            3 25 14.7 0 2.3                                                               4 25 14.7 14.1 2.1                                                            5 15 0 14.1 8.3                                                               6 15 14.7 0 4.3                                                               7 15 14.7 14.1 3.3                                                          ______________________________________                                    

The smallest particle size (and hence the best stability) is achieved ifthe product has an active concentration after the first stage of 25%.This concentration is close to the phase transition (30%) between thecontinuous or lamella sheet phase (>30%) to a dispersed phase (<30%).The higher viscosity is believed to enhance the action of shear andextension. The smallest particle size is achieved where shear andextension were both applied. A comparison of Control 2 and Samples2,3,4,7 shows that a smaller particle size is obtained at lower levelsof shear and/or extension than for high shear alone. Products of higherconcentration can be made compared to the conventional process.

EXAMPLE 4

Various concentrated fabric washing products were formed, all having theformulation listed in Table 4.1. All components except for the water areconsidered as "active components" within the meaning of the invention.

Pastes (initial mixture) were formed in a batch mixer of the Z bladetype. The paste ingredients were selected from those detailed in Table4.1 and added in the order shown in Table 4.2. Sufficient water wasadded to form pastes with an surfactant concentration relative to thewater content as shown in Table 4.2. The remaining water and otheringredients were included as the diluent stream during the later mixingstep. For simplicity the sodium hydroxide is included with surfactantssince it was added in the Z blade mixer to neutralise the PRIOLENE. Thepaste formed was a lamellar liquid crystal phase. The pastes viscositieswere measured and are listed in Table

                  TABLE 4.1                                                       ______________________________________                                                   Ingredient                                                                             % as received                                             ______________________________________                                        Water (W)    Demin water                                                                              29.5                                                    Electrolyte Glycerol 2                                                        (E) Borax 1.5                                                                  Sodium 9.2                                                                    citrate                                                                      Solid (S) Vegabond XD 18.7                                                    Polymer (P) Narlex DC1 3.0                                                    Surfactant Synperonic A7 4.5                                                  (A) Synperonic A3 4.5                                                          Na LAS 20.7                                                                   Priolene 4.5                                                                  NaOH (47%) 1.3                                                               Minors Tinopal CBS-X 0.1                                                       Antifoam 0.3                                                               ______________________________________                                    

                  TABLE 4.2                                                       ______________________________________                                        Paste         Surfactant (A)                                                    constituents & concentration wrt Viscosity at 20/s                            order of addition water (mPas)                                              ______________________________________                                        WESPA         70          11,000                                                WESA 70 >100,000                                                              WSPA (1) 70 >20,000                                                           SPAW 70 >20,000                                                               WSPA (2) 60 >20,000                                                           WSA 70 26,000                                                               ______________________________________                                    

The diluent was formed in a conventional design of stirred tank atambient temperature. The paste and diluent were injected into a shorttube which led to the inlet port of mixer as employed in Example 2. Thepaste temperature was 35 to 55° C. Flow rates were employed to provide aproduct flow rate of about 20 kg/hr resulting in a long residence timein the mixer of the order of 3 min. The temperature of the ingredientswas increased by heating the mixer to about 70-80° C. resulting in exittemperatures which were similar to the paste temperatures. Typical shearrates were in the range 3.5 to 10.5×10³ /S. The final products containeda dispersed liquid crystal phase.

A product having the composition in Table 4.1 was produced by aconventional batch method for comparative purposes.

The relative refractive index and viscosity of the final products weredetermined and the results are detailed in Table 4.3.

Results

                  TABLE 4.3                                                       ______________________________________                                        Paste                                                                           constituents &  Viscosity at                                                  order of addition RRI 25                                                                          ° C. & 20/s                                      ______________________________________                                        Batch control  78     740                                                       WESPA 103 1920                                                                WESA 99 1500                                                                  WSPA(1) 98 750                                                                SPAW 96 660                                                                   WSPA(2) 102 1010                                                              WSA 100 1050                                                                ______________________________________                                    

The results demonstrate that products of comparable viscosity to theconventional produced product can be made but with a much smallerparticle size (indicated by a high increase in RRI) and hence betterstability. For similar RRI lower viscosity product is obtained byexcluding the electrolyte from the paste and adding it to the diluentstream. A comparison of WSPA(1) with SPAW illustrates that the order ofaddition in forming the paste does not have a major effect on the finalproduct properties. Similar final product properties were achieved usinga higher level of water in the paste (compare WSPA(1) with WSPA(2)).This is beneficial in practice as the process is not significantlyaffected by fluctuations in the water content of feedstock materials.

Comparative Tests

As a comparative test, two pastes (WESPA and WSPA as shown in table 4.2)were prepared in a small Z blade mixer (600 ml) and then diluted in thesame mixer. Small aliquots of diluent (each 5wt%) were then added eachover 1 minute but this resulted in clogging around the rotor andrequired the mixer to be periodically stopped to dislodge the paste.

This test demonstrated that the use of conventional batch mixers whichare suitable for conventional mixing of pastes is not feasible. Thecompositions obtained had very high viscosities and were unacceptable.

A further set of comparative tests were conducted by forming pastes aslisted in Table 4.2 and attempting to dilute them in a conventionalbatch stirred tank. It was found that the pastes tended to break intolumps and not disperse easily.

EXAMPLE 5

A concentrated fabric washing composition was formed by the followingprocess. A paste was formed in a batch mixer of the Z blade type bymixing the ingredients shown in Table 5.1 in the listed order. The pasteformed a lamellar liquid crystal phase and had a viscosity of 98,00 mPasmeasured at 40° C. & 20/s. The homogeneity of the paste was tested by bymeasuring the RRI of 10 samples of the paste taken randomly from thebatch. The spread of RRI measurements for all the samples was provided amean RRI of 161.5, with a standard deviation of 1.6.

The diluent stream was formed in a conventional design of stirred tankat about 80° C. (due to the heat of neutralisation). The diluent streamwas added to the paste in one step in-a mixing device having a shear andextension zone as referred to in Example 2. The combined flow rate ofthe two streams was 220-230 kg/hr. The shear and extension rates werealtered to produce a different product as shown in Table 5.2.

The final product contained a dispersed liquid crystal phase.

                  TABLE 5.1                                                       ______________________________________                                        Ingredient      Paste  Diluent stream                                         ______________________________________                                        Synperonic A7   4.5                                                             Synperonic A3 4.5                                                             LAS 21.0                                                                      KOH (47%) 5.7                                                                 Wessalith P 18.7                                                              Narlex DC1 3.0                                                                Antifoam 0.5                                                                  Tinopal CBS-X 0.1                                                             TOTAL 58.1                                                                    Demin water  15.5                                                             Glycerol  2                                                                   Borax  1.5                                                                    KOH (49%)  14.4                                                               Citric acid  8.5                                                              TOTAL  41.9                                                                 ______________________________________                                    

                  TABLE 5.2                                                       ______________________________________                                        Shear   Extenson   Viscosity (mPas)                                                                            RRI                                          rate    rate               4 wks at     4 wks at                                ×10.sup.3 /s (×10.sup.3 /s) Initial 20° C. Initial                                               20° C.                         ______________________________________                                        4.4     0          700     +250    84   +3                                      44.0 0 790 -190 108 +1                                                        4.4 16.0 1000 +50 96 +4                                                       44.0 16.0 720 -90 111 +2                                                    ______________________________________                                    

The results illustrate that at low shear, application of extensionproduces significantly smaller droplets in the product and at highershear, optionally with extension, much smaller droplets may be obtainedat a comparable viscosity to low shear and with a downward drift inviscosity. The products were acceptably stable over 4 weeks.

EXAMPLE 6

A concentrated fabric washing product having the composition listed inTable 6.1 was produced in the following way. The active component premixwas a liquid and was made in a stirred tank. The diluent stream was alsoa liquid and was prepared in a stirred tank where its temperature wasmaintained at about 80° C. due to the neutralisation of the citric acid.The active stream and half of the diluent (electrolyte) stream werebrought together in a mixing device as employed in Example 2 to form apaste/gel having a viscosity of 19,000 mPas measured at 40° C. & 20/s.

The remainder of the diluent stream was then injected into the processstream at a downstream point in the mixer to form the final product. Thecombined flow rate of the streams was of the order of 190-210 kg/hr. Theshear rate applied to the product stream was varied as shown in Table6.2 below.

For comparative purposes, a 40 L batch of the product was made in theconventional way by adding the ingredients to water in a stirred tank.Part of the comparative sample was subsequently subjected to shear on aDispax high shear mixer. The results are presented as the first threesamples in Table

                  TABLE 6.1                                                       ______________________________________                                                        Actives                                                                             Electrolyte                                               premix premix                                                               ______________________________________                                        LAS acid          26.1                                                          Synperonic A7 12.1                                                            Demin water 0.7                                                               TOTAL 38.9                                                                    Demin water  20.2                                                             Glycerol  5.0                                                                 Borax (decahydrate)  3.5                                                      Citric acid  6.5                                                              (anhydrous)                                                                   Sodium hydroxide  17.3                                                        Sodium carbonate  4.0                                                         Narlex DC1  4.5                                                               TOTAL  61.0                                                                 ______________________________________                                    

                  TABLE 6.2                                                       ______________________________________                                               Shear Median particle      Viscosity                                     (×10.sup.3 /s) size (μm) Viscosity 4 wks 37° C.             ______________________________________                                        Batch    0.1-0.5 4.6         500    Unstable                                    Batch + PS 30 2.2 420 +20                                                     Batch + PS 82 1.3 740 -130                                                    1 4.4 4.1 370 Unstable                                                        2 14.1 1.5 290 -10                                                            3 24.0 1.0 340 +10                                                            4 33.8 0.84 650 -30                                                         ______________________________________                                    

Application of a minimum level of shear is desirable in order to providea product which remains stable after 4 weeks. The results alsodemonstrate that generally lower viscosity stable products were producedusing the process according to the invention in which homogeneity wasmaintained rather than by conventional means. Furthermore, at comparableshear rates the process of the invention provides a smaller particlesize which enhances product stability.

EXAMPLE 7

A conventionalk strength fabric washing liquid composition was producedaccording to the following process. The composition of the final productis shown in Table 7.1.

The paste was made batchwise using a Z-blade mixer and had a viscositygreater than 200,000 mPas measured at 40° C. & 20/s. The homogeneity ofthe paste was determined by making RRI measurements of 10 samples takenrandomly from the batch. The mean RRI was 125.3 with a standarddeviation of the sample of 0.9.

The remaining ingredients were mixed together in a conventional stirredtank to form the diluent stream. The paste was fed into the mixerreferred to in Example 2 and the diluent stream was injected in twostages prior to the extension portion of the mixer. The combined flowrate of the streams was between 190-210 kg/hr and the shear rate wasvaried as detailed in Table 7.2.

                  TABLE 7.1                                                       ______________________________________                                        Ingredients        Paste  Diluent                                             ______________________________________                                        LAS acid (Vista)   7.0                                                          Synperonic A7 3.6                                                             Synperonic A3 1.0                                                             Sodium hydroxide 2.0                                                          Zeolite 25.0                                                                  Antifoam 0.2                                                                  Dequest 2066 2.4                                                              Sodium xylene 2.0                                                             sulphonate                                                                    TOTAL 43.2                                                                    Demin water  43.6                                                             Citric acid  2.3                                                              (anhydrous)                                                                   Sodium hydroxide  1.0                                                         Glycerol  5                                                                   Borax  4                                                                      (decahydrate)                                                                 Calcium Chloride  0.15                                                        Sokolan PA50  0.45                                                            TOTAL  56.5                                                                 ______________________________________                                    

For comparative purposes, a product having the same composition butproduced in a conventional stirred tank optionally with post-shear wasalso produced. The viscosity and RRI data for these materials are alsoshown in Table 7.2

                  TABLE 7.2                                                       ______________________________________                                        Shear       Viscosity (mPas)                                                                             RRI                                                (×10.sup.3 /s)                                                                      Initial 2 wks, 20° C.                                                                     Initial                                                                            2 wks, 20° C.                      ______________________________________                                        1       4.4      717    +59      56   0                                         2 44.0  650 -2 53 -1                                                          Control 0.1-0.5 1180  51                                                      stirred                                                                       tank                                                                          Control 32.0 1090  51                                                         stirred                                                                       tank + PS                                                                   ______________________________________                                    

The process of the present invention allows a product having a lowerviscosity and smaller droplet size to be prepared as compared to theconventional route which even with high post-shear gives a product whichhas an unacceptably high viscosity.

EXAMPLE 8

This Example illustrates the use of the apparatus according to theinvention for the production of a stable fabric washing liquidcomposition.

A product having the formulation shown in Table 8.1 was prepared in theconventional manner using a stirred tank. The ingredients were added inthe order shown in the Table. The product was then exposed toextensional flow optionally with shear by passing it through the mixingdevice referred to in Example 2 under the conditions specified in Table8.2.

The products were initially stable and their stability was checked after8 weeks.

                  TABLE 8.1                                                       ______________________________________                                        Ingredients    % as received                                                  ______________________________________                                        Demin water    32.1                                                             Citric acid 5.5                                                               Glycerol 5.0                                                                  Borax 3.5                                                                     Tinopal CBS-X 0.1                                                             NaOH (47%) 14.3                                                               Narlex DC1 2.15                                                               Synperonic A7 10.8                                                            Priolene 6902 7.55                                                            Prifac 7904 5.0                                                               LAS 13.0                                                                      Perfume 0.35                                                                  Antifoam 0.1                                                                  Dequest 0.55                                                                ______________________________________                                    

                  TABLE 8.2                                                       ______________________________________                                                 Shear rate    Extension                                                                              Stable at                                       Sample (/s) rate (s) 8 weeks                                                ______________________________________                                        Control  0.1-0.5       0        No                                              2 0 >22 000 No                                                                2 2000 8 500 No                                                               3 15000 8 500 Yes                                                           ______________________________________                                    

The results show that a product having good stability may be obtainedwith a suitable combination of shear and extension.

We claim:
 1. A process for the production of a structured cleaning orfabric conditioning liquid composition comprising a surfactant activecomponent and a diluent selected from the group consisting of water,aqueous solutions and surfactants, with the proviso that any diluentsurfactant is immiscible with the surfactant active component, theprocess comprising:i) mixing an active component of the composition witha liquid active component, part of the diluent or both to produce asubstantially homogeneous liquid crystal mixture, wherein the activecomponent, the liquid active component or both contain a surfactant; ii)incorporating the diluent to saturate the liquid crystal mixture withrespect to the diluent whereby a substantially homogeneous continuousphase comprising the active component and diluent, and optionally adispersed phase comprising the diluent, is produced; iii) producing asubstantially homogeneous dispersion of the saturated liquid crystalmixture in a continuous diluent phase; and iv) optionally diluting thedispersion with further diluent to provide the desired concentration ofactive component; v) wherein the mixture is subjected to an extensionalflow rate of more than about 3×10³ sec⁻¹ and a shear rate of more than3×10³ sec⁻¹ in progressing from step (ii) to step (iii).
 2. A processaccording to claim 1 ,in which at least 50 weight % of the liquidcrystal mixture comprises at least one active component.
 3. A processaccording to claim 1 in which the dispersion has an average droplet sizeof less than 10 μm.
 4. A process according to claim 1 in which theliquid crystal mixture is lamellar and is in, or passes through the Lαphase, directly or indirectly into the L₁ +L.sub.α phase during orsubsequent to the addition of the diluent to the initial mixture.
 5. Aprocess according to claim 1 in which the active component comprises ananionic, nonionic, caronic or zwitterionic surfactant or mixturesthereof.
 6. A process for producing an aqueous liquid compositionaccording to claim 2 in which the diluent comprises water.